1. Field of the Invention
The present invention pertains to endoscopic imaging. More particularly, the present invention pertains to a method and system for providing accurate visualization and measurement of endoscopic images.
2. Description of the Related Art
As known in the art, endoscopic devices such as endoscopes provide visual examination of the interior of hollow structures such as human organs, pipelines, gun barrels, etc. For example, a medical doctor can use an endoscopic device to examine Barrett's metaplasia of a patient's esophagus to track the progression of the disease; a chemical engineer can use an endoscopic device to examine the inside of a pipeline to check for erosion; or a law enforcement agent can use an endoscopic device to map out the interior of a gun barrel for ballistic fingerprinting. Today, there is virtually an endoscopic device available for every single orifice and structure that needs to be examined.
A major problem with the conventional endoscopic device is that it tends to distort the image of a region under examination, which in turn can prevent a correct assessment of the examined region. For instance, the current inability of endoscopic devices to precisely measure the area of esophageal involvement by Barrett's metaplasia precludes an accurate assessment of the natural history of the disease, and patient disposition to developing adenocarcinoma. Typically, the image distortion created by a conventional endoscopic device is caused by the lens employed in the endoscopic device and/or the curvature of the wall of the region under examination. In an attempt to rectify the image distortion problem, the inventor, with collaboration from others, developed a computer imaging method (hereinafter, “the prior imaging method”) to create accurate two-dimensional color maps from endoscopic photographs. The method was based on the premise that by combining information contained in the photographed endoscopic image with a knowledge of the geometry of the region under examination and the nature of the lens distortion, a more accurate visualization of the region is possible. The method provides correction for the distortion of the endoscopic lens, calculates the center of the circular endoscopic photograph after the user identifies the perimeter of the image, recreates a three-dimensional cylindrical image of the region under examination, and “unrolls” or transforms it into a planar image. The resulting unrolled planar images are stacked in sequence to produce a two-dimensional map of the photographed model. The perimeter of the region in the two-dimensional map is then manually traced, and the area under the curve is color filled and calculated. A more detailed description of the prior imaging method is disclosed in a published article titled, “Computer Enhanced Endoscopic Visualization,” which is herein incorporated by reference in its entirety.